1. Field of the Invention
The present invention relates to an apparatus and method for image pickup. More particularly, the present invention relates to an apparatus and method for reducing noise and the effect of shaking in an image.
2. Description of the Related Art
Several conventional techniques exist for reducing the effect of shaking on a photographic image. For example, one method shifts a position of a lens with respect to a photographing surface in a direction opposite to that in which the photographer's hand is shaking to reduce the effect of the shaking when taking pictures. In another method, a plurality of images are photographed using a high-speed shutter, and the photographed images are combined based on characteristic points of the photographed subject to electronically reduce the effect of shaking, as disclosed in Japanese Laid-open Patent No. 2005-295302. That method is particularly effective to photograph images using low shutter speed where there is a low intensity of light. In addition, Japanese Laid-open Patent No. 2003-116064 discloses a method of removing fixed pattern noise by subtracting images photographed in a dark state from an image photographed in an exposure state, in a low light intensity environment.
According to a conventional noise reduction method, a plurality of images taken using time-division exposure (hereinafter referred to as time-division images) photographed using a high shutter speed are combined, and images photographed in a dark state using low shutter speed are subtracted from the combined images to reduce the fixed pattern noise. However, if the electronic shaking reduction technique and the technique of subtracting the dark frames are combined, the time-division images including fixed pattern noises are combined. In this event, the fixed pattern noise of each image is distributed in the image area, and thus, the fixed pattern noises are not accurately removed when the dark frames are subtracted from the combined image.